Generally yes. Talemetry Broadcast supports the ability to modify existing job postings. Within an existing job posting, you can (a) add one or more new job boards to the posting, (b) remove an existing job board from the posting, or (c) change the content of the job posting (for example, the job description).
NOTE: There are some boards that do not support the ability to modify a posting once it is posted. Information on what board support modifications is available from Talent Technology Client Services.